I’ve never sold any, but the comments I’ve read here on BYC is $30 for known pullets that are purebred. $10 for mixed breeds and $5 for roosters. But you can always ask for more and be open to people haggling. But supply and demand play a major factor on how much you sell them for.
Hopefully someone with more experience actually selling chickens can offer some insight.
ETA: Keep track of your expenses such as feed, water, bedding, time (since time is money

) and divide that information by how many chicks used those items and as long as you sell them more than what your expenses were, the habit will be worth it.